The present invention concerns muntin bars used for separating window panes of large size into smaller size panes to enhance the appearance of a window.
Windows constructed from multiple glass panes utilized xe2x80x9cmuntinsxe2x80x9dor xe2x80x9cmuntin barsxe2x80x9d to secure the edges of the individual glass panes within the window sash. In many windows, muntins formed distinctive grid patterns that are associated with architectural styles of buildings containing the windows.
Modern windows formed by insulating glass units utilize single glass lights separated by an insulating dead air space. Where a particular architectural xe2x80x9clookxe2x80x9d is desired, a grid of muntin bars is fixed in the dead air space between the glass lights to simulate a multi-pane window. Typical muntin bars for insulating glass units are formed from decoratively coated interfitted metal tubes. The grids are anchored to the insulating glass unit periphery.
Constructing muntin bar grids for insulating glass units has been a labor intensive process. As a consequence, manufacturing such units, and thus windows formed by the units, has been costly and inefficient. Some efforts to automate the manufacture of muntin grids have been made. Commonly owned U.S. Pat. No. 6,173,484 entitled xe2x80x9cSystem for Fabricating Muntin Bars from Sheet Materialxe2x80x9d which issued Jan. 16, 2001 to McGlinchy et al. is an example of a system for automated fabrication of muntin bars. The subject matter of the ""484 patent is incorporated herein by reference. Commonly owned pending U.S. patent application Ser. No. 09/525,349 entitled xe2x80x9cSystem for Fabricating Contour Muntin Bars from Sheet Materialxe2x80x9d is a second patent application to McGlinchy et al concerning automated fabrication of so-called contour muntin bars and the subject matter of this application is incorporated herein by reference.
The muntin bar stock is produced by roll forming decoratively coated sheet material such as aluminum or steel, in a known manner. Various sizes of the sheet material are used to form different size muntin bar stock. The roll forming machine has a series of rolls configured to form the sheet material into elongated tubular muntin bar stock. A window manufacturer purchases the muntin bar stock size(s) needed to produce insulating glass units. Apparatus disclosed in the aforementioned patent application also cuts the stock into lengths that are notched in appropriate locations for assembly into grids for incorporation into the insulating glass units.
The residential window and door industry has witnessed an increased in demand for decorative muntin bars contained inside insulated glass (IG) units of windows. The demand for muntin bars has increased due to popular xe2x80x9ccolonial lookxe2x80x9d trends in the market which has increased the demand for muntin bars. Also contributing to the demand are new construction and residential building codes requiring a common facade in local neighborhoods. With people also desiring differentiation and designer choices in their windows, a demand for so-called xe2x80x9ctwo tonexe2x80x9d muntin bars is also on the rise. The two tone muntin bar presents one appearance from the outside and a second appearance from inside the window.
Two-tone muntin bars are offered today in many color combinations for both rectangular and contour style muntin bars. A two-tone muntin bar demands a premium price in the market place. One reason for the increased price of two tone muntin bars is the fact that automated manufacturing of two tone muntin bars using controlled notching, roll forming and severing has not occurred.
The most common method practiced at the present time for manufacturing two tone muntin grids starts with a long roll formed bar that is often shipped to a secondary supplier that paints or laminates the bar with a solid color tone or pattern on one side and a second color or pattern on the opposite side. Use of multiple steps performed by multiple suppliers results in significant additional cost to the final assembled product. More elaborate bars have simulated wood grains that are used to match up with the wood trim in or surrounding the window sash. All of the current methods require cutting specified length segments from a two tone bar. The bar is then mitred and/or punched to complete fabrication of the muntin bar. The current methods require post painting and/or lamination which are time consuming, costly and provide limited throughput. This requirement also leads to a build up of inventory to give the suppliers adequate lead time for performing these post roll forming procedures.
The present invention concerns an automated method and apparatus for producing laminated muntin bars. Sheet material is roll formed into either rectangular or contour muntin bars and then covered with laminating material. In accordance with one exemplary process muntin bars are provided that have one appearance when viewed from outside the window and a second appearance when viewed from inside the window.
A process for making muntin bars in accordance with the invention includes providing an elongated preformed muntin bar member that has been treated on a portion of an exposed surface of the muntin bar member. An elongated strip of covering material is also provided for controlled application onto a specified portion of the treated portion of the muntin bar material. The elongated strip of covering material includes an adhesive for adhering the covering material to the muntin bar member. The muntin bar member and the covering material are brought into contact with each other while applying heat and pressure to cause the covering material to overlie and adhere to the muntin bar member.
When making two tone muntin bars, one exemplary embodiment of the invention starts with an elongated strip of muntin bar material that has been painted on at least one side. The strip is roll formed to form an elongated generally hollow bar. The painted surface of the elongated bar is then covered with a covering material that is brought into contact with the painted surface to alter an appearance of the muntin bar material. More specifically, the covering material covers one half of an exterior, painted surface of the muntin bar material to form a two tone muntin bar member.
Practice of the invention allows the laminated muntin bars to be produced on an as needed basis. A coil of strip that has been painted and treated with a second color on one half of its surface is then stored in inventory. This inventory is bent by rollforming equipment and then coated with a covering material on an as needed basis. This is to contrasted with a prior art process of fabricating muntin bars which must be shipped to a supplier and secondly shipped back to the window fabricator for inclusion in an IGU. There is a cost savings as well as a savings in time especially where the inventory is maintained at the same location that the muntin bar fabrication occurs.
The disclosed embodiment of the invention uses a flexible elongated multilayer strip or foil of covering material that is applied to a painted surface of preformed muntin bar material. One layer of the flexible elongated multilayer strip or foil has an appearance which is visible on a muntin bar fabricated from the mutlilayer strip. A second, adhesive layer causes the first, appearance defining layer to adhere to a preformed muntin bar memeber. The foil also includes a carrier layer for supporting the first layer as the multilayer strip or foil is brought into contact with the preformed muntin bar member.
These and other objects, advantages and features of the invention win become better understood from a review of the exemplary embodiment of the invention which is described in conjunction with the accompanying drawings.